package Chaines.Variables is
   type Chaine_Variable is private;

   function Chainer(S: String) return Chaine_Variable;
   function Chainer(P: Chaine_Variable) return Chaine_Variable;
   function Dechainer(P:Chaine_Variable) return String;
   function Lire_Ligne return Chaine_Variable;
   procedure Ecrire(C: Chaine_Variable);
   function Concat(C1,C2:Chaine_Variable) return Chaine_Variable;
   function Tri(C:Chaine_Variable) return Chaine_Variable;
   function Equal (C1,c2 : Chaine_Variable) return Boolean;
private
   type Chaine_Variable is access String;
end Chaines.Variables;
